/**
 * Copyright (c) 2006-2015, JGraph Ltd
 * Copyright (c) 2006-2015, Gaudenz Alder
 */
/**
 * Class: mxFastOrganicLayout
 *
 * Extends <mxGraphLayout> to implement a fast organic layout algorithm.
 * The vertices need to be connected for this layout to work, vertices
 * with no connections are ignored.
 *
 * Example:
 *
 * (code)
 * var layout = new mxFastOrganicLayout(graph);
 * layout.execute(graph.getDefaultParent());
 * (end)
 *
 * Constructor: mxCompactTreeLayout
 *
 * Constructs a new fast organic layout for the specified graph.
 */
function mxFastOrganicLayout(graph)
{
    mxGraphLayout.call(this, graph);
};

/**
 * Extends mxGraphLayout.
 */
mxFastOrganicLayout.prototype = new mxGraphLayout();
mxFastOrganicLayout.prototype.constructor = mxFastOrganicLayout;

/**
 * Variable: useInputOrigin
 *
 * Specifies if the top left corner of the input cells should be the origin
 * of the layout result. Default is true.
 */
mxFastOrganicLayout.prototype.useInputOrigin = true;

/**
 * Variable: resetEdges
 *
 * Specifies if all edge points of traversed edges should be removed.
 * Default is true.
 */
mxFastOrganicLayout.prototype.resetEdges = true;

/**
 * Variable: disableEdgeStyle
 *
 * Specifies if the STYLE_NOEDGESTYLE flag should be set on edges that are
 * modified by the result. Default is true.
 */
mxFastOrganicLayout.prototype.disableEdgeStyle = true;

/**
 * Variable: forceConstant
 *
 * The force constant by which the attractive forces are divided and the
 * replusive forces are multiple by the square of. The value equates to the
 * average radius there is of free space around each node. Default is 50.
 */
mxFastOrganicLayout.prototype.forceConstant = 50;

/**
 * Variable: forceConstantSquared
 *
 * Cache of <forceConstant>^2 for performance.
 */
mxFastOrganicLayout.prototype.forceConstantSquared = 0;

/**
 * Variable: minDistanceLimit
 *
 * Minimal distance limit. Default is 2. Prevents of
 * dividing by zero.
 */
mxFastOrganicLayout.prototype.minDistanceLimit = 2;

/**
 * Variable: minDistanceLimit
 *
 * Minimal distance limit. Default is 2. Prevents of
 * dividing by zero.
 */
mxFastOrganicLayout.prototype.maxDistanceLimit = 500;

/**
 * Variable: minDistanceLimitSquared
 *
 * Cached version of <minDistanceLimit> squared.
 */
mxFastOrganicLayout.prototype.minDistanceLimitSquared = 4;

/**
 * Variable: initialTemp
 *
 * Start value of temperature. Default is 200.
 */
mxFastOrganicLayout.prototype.initialTemp = 200;

/**
 * Variable: temperature
 *
 * Temperature to limit displacement at later stages of layout.
 */
mxFastOrganicLayout.prototype.temperature = 0;

/**
 * Variable: maxIterations
 *
 * Total number of iterations to run the layout though.
 */
mxFastOrganicLayout.prototype.maxIterations = 0;

/**
 * Variable: iteration
 *
 * Current iteration count.
 */
mxFastOrganicLayout.prototype.iteration = 0;

/**
 * Variable: vertexArray
 *
 * An array of all vertices to be laid out.
 */
mxFastOrganicLayout.prototype.vertexArray;

/**
 * Variable: dispX
 *
 * An array of locally stored X co-ordinate displacements for the vertices.
 */
mxFastOrganicLayout.prototype.dispX;

/**
 * Variable: dispY
 *
 * An array of locally stored Y co-ordinate displacements for the vertices.
 */
mxFastOrganicLayout.prototype.dispY;

/**
 * Variable: cellLocation
 *
 * An array of locally stored co-ordinate positions for the vertices.
 */
mxFastOrganicLayout.prototype.cellLocation;

/**
 * Variable: radius
 *
 * The approximate radius of each cell, nodes only.
 */
mxFastOrganicLayout.prototype.radius;

/**
 * Variable: radiusSquared
 *
 * The approximate radius squared of each cell, nodes only.
 */
mxFastOrganicLayout.prototype.radiusSquared;

/**
 * Variable: isMoveable
 *
 * Array of booleans representing the movable states of the vertices.
 */
mxFastOrganicLayout.prototype.isMoveable;

/**
 * Variable: neighbours
 *
 * Local copy of cell neighbours.
 */
mxFastOrganicLayout.prototype.neighbours;

/**
 * Variable: indices
 *
 * Hashtable from cells to local indices.
 */
mxFastOrganicLayout.prototype.indices;

/**
 * Variable: allowedToRun
 *
 * Boolean flag that specifies if the layout is allowed to run. If this is
 * set to false, then the layout exits in the following iteration.
 */
mxFastOrganicLayout.prototype.allowedToRun = true;

/**
 * Function: isVertexIgnored
 *
 * Returns a boolean indicating if the given <mxCell> should be ignored as a
 * vertex. This returns true if the cell has no connections.
 *
 * Parameters:
 *
 * vertex - <mxCell> whose ignored state should be returned.
 */
mxFastOrganicLayout.prototype.isVertexIgnored = function(vertex)
{
    return mxGraphLayout.prototype.isVertexIgnored.apply(this, arguments) ||
        this.graph.getConnections(vertex).length == 0;
};

/**
 * Function: execute
 *
 * Implements <mxGraphLayout.execute>. This operates on all children of the
 * given parent where <isVertexIgnored> returns false.
 */
mxFastOrganicLayout.prototype.execute = function(parent)
{
    var model = this.graph.getModel();
    this.vertexArray = [];
    var cells = this.graph.getChildVertices(parent);

    for (var i = 0; i < cells.length; i++)
    {
        if (!this.isVertexIgnored(cells[i]))
        {
            this.vertexArray.push(cells[i]);
        }
    }

    var initialBounds = (this.useInputOrigin) ?
        this.graph.getBoundingBoxFromGeometry(this.vertexArray) :
        null;
    var n = this.vertexArray.length;

    this.indices = [];
    this.dispX = [];
    this.dispY = [];
    this.cellLocation = [];
    this.isMoveable = [];
    this.neighbours = [];
    this.radius = [];
    this.radiusSquared = [];

    if (this.forceConstant < 0.001)
    {
        this.forceConstant = 0.001;
    }

    this.forceConstantSquared = this.forceConstant * this.forceConstant;

    // Create a map of vertices first. This is required for the array of
    // arrays called neighbours which holds, for each vertex, a list of
    // ints which represents the neighbours cells to that vertex as
    // the indices into vertexArray
    for (var i = 0; i < this.vertexArray.length; i++)
    {
        var vertex = this.vertexArray[i];
        this.cellLocation[i] = [];

        // Set up the mapping from array indices to cells
        var id = mxObjectIdentity.get(vertex);
        this.indices[id] = i;
        var bounds = this.getVertexBounds(vertex);

        // Set the X,Y value of the internal version of the cell to
        // the center point of the vertex for better positioning
        var width = bounds.width;
        var height = bounds.height;

        // Randomize (0, 0) locations
        var x = bounds.x;
        var y = bounds.y;

        this.cellLocation[i][0] = x + width / 2.0;
        this.cellLocation[i][1] = y + height / 2.0;
        this.radius[i] = Math.min(width, height);
        this.radiusSquared[i] = this.radius[i] * this.radius[i];
    }

    // Moves cell location back to top-left from center locations used in
    // algorithm, resetting the edge points is part of the transaction
    model.beginUpdate();
    try
    {
        for (var i = 0; i < n; i++)
        {
            this.dispX[i] = 0;
            this.dispY[i] = 0;
            this.isMoveable[i] = this.isVertexMovable(this.vertexArray[i]);

            // Get lists of neighbours to all vertices, translate the cells
            // obtained in indices into vertexArray and store as an array
            // against the orginial cell index
            var edges = this.graph.getConnections(this.vertexArray[i], parent);
            var cells = this.graph.getOpposites(edges, this.vertexArray[i]);
            this.neighbours[i] = [];

            for (var j = 0; j < cells.length; j++)
            {
                // Resets the points on the traversed edge
                if (this.resetEdges)
                {
                    this.graph.resetEdge(edges[j]);
                }

                if (this.disableEdgeStyle)
                {
                    this.setEdgeStyleEnabled(edges[j], false);
                }

                // Looks the cell up in the indices dictionary
                var id = mxObjectIdentity.get(cells[j]);
                var index = this.indices[id];

                // Check the connected cell in part of the vertex list to be
                // acted on by this layout
                if (index != null)
                {
                    this.neighbours[i][j] = index;
                }

                // Else if index of the other cell doesn't correspond to
                // any cell listed to be acted upon in this layout. Set
                // the index to the value of this vertex (a dummy self-loop)
                // so the attraction force of the edge is not calculated
                else
                {
                    this.neighbours[i][j] = i;
                }
            }
        }
        this.temperature = this.initialTemp;

        // If max number of iterations has not been set, guess it
        if (this.maxIterations == 0)
        {
            this.maxIterations = 20 * Math.sqrt(n);
        }

        // Main iteration loop
        for (this.iteration = 0; this.iteration < this.maxIterations; this.iteration++)
        {
            if (!this.allowedToRun)
            {
                return;
            }

            // Calculate repulsive forces on all vertices
            this.calcRepulsion();

            // Calculate attractive forces through edges
            this.calcAttraction();

            this.calcPositions();
            this.reduceTemperature();
        }

        var minx = null;
        var miny = null;

        for (var i = 0; i < this.vertexArray.length; i++)
        {
            var vertex = this.vertexArray[i];

            if (this.isVertexMovable(vertex))
            {
                var bounds = this.getVertexBounds(vertex);

                if (bounds != null)
                {
                    this.cellLocation[i][0] -= bounds.width / 2.0;
                    this.cellLocation[i][1] -= bounds.height / 2.0;

                    var x = this.graph.snap(Math.round(this.cellLocation[i][0]));
                    var y = this.graph.snap(Math.round(this.cellLocation[i][1]));

                    this.setVertexLocation(vertex, x, y);

                    if (minx == null)
                    {
                        minx = x;
                    }
                    else
                    {
                        minx = Math.min(minx, x);
                    }

                    if (miny == null)
                    {
                        miny = y;
                    }
                    else
                    {
                        miny = Math.min(miny, y);
                    }
                }
            }
        }

        // Modifies the cloned geometries in-place. Not needed
        // to clone the geometries again as we're in the same
        // undoable change.
        var dx = -(minx || 0) + 1;
        var dy = -(miny || 0) + 1;

        if (initialBounds != null)
        {
            dx += initialBounds.x;
            dy += initialBounds.y;
        }

        this.graph.moveCells(this.vertexArray, dx, dy);
    }
    finally
    {
        model.endUpdate();
    }
};

/**
 * Function: calcPositions
 *
 * Takes the displacements calculated for each cell and applies them to the
 * local cache of cell positions. Limits the displacement to the current
 * temperature.
 */
mxFastOrganicLayout.prototype.calcPositions = function()
{
    for (var index = 0; index < this.vertexArray.length; index++)
    {
        if (this.isMoveable[index])
        {
            // Get the distance of displacement for this node for this
            // iteration
            var deltaLength = Math.sqrt(this.dispX[index] * this.dispX[index] +
                this.dispY[index] * this.dispY[index]);

            if (deltaLength < 0.001)
            {
                deltaLength = 0.001;
            }

            // Scale down by the current temperature if less than the
            // displacement distance
            var newXDisp = this.dispX[index] / deltaLength
                * Math.min(deltaLength, this.temperature);

            var newYDisp = this.dispY[index] / deltaLength
                * Math.min(deltaLength, this.temperature);

            // reset displacements
            this.dispX[index] = 0;
            this.dispY[index] = 0;

            // Update the cached cell locations
            this.cellLocation[index][0] += newXDisp;
            this.cellLocation[index][1] += newYDisp;
        }
    }
};

/**
 * Function: calcAttraction
 *
 * Calculates the attractive forces between all laid out nodes linked by
 * edges
 */
mxFastOrganicLayout.prototype.calcAttraction = function()
{
    // Check the neighbours of each vertex and calculate the attractive
    // force of the edge connecting them
    for (var i = 0; i < this.vertexArray.length; i++)
    {
        for (var k = 0; k < this.neighbours[i].length; k++)
        {
            // Get the index of the othe cell in the vertex array
            var j = this.neighbours[i][k];

            // Do not proceed self-loops
            if (i != j &&
                this.isMoveable[i] &&
                this.isMoveable[j])
            {
                var xDelta = this.cellLocation[i][0] - this.cellLocation[j][0];
                var yDelta = this.cellLocation[i][1] - this.cellLocation[j][1];

                // The distance between the nodes
                var deltaLengthSquared = xDelta * xDelta + yDelta
                    * yDelta - this.radiusSquared[i] - this.radiusSquared[j];

                if (deltaLengthSquared < this.minDistanceLimitSquared)
                {
                    deltaLengthSquared = this.minDistanceLimitSquared;
                }

                var deltaLength = Math.sqrt(deltaLengthSquared);
                var force = (deltaLengthSquared) / this.forceConstant;

                var displacementX = (xDelta / deltaLength) * force;
                var displacementY = (yDelta / deltaLength) * force;

                this.dispX[i] -= displacementX;
                this.dispY[i] -= displacementY;

                this.dispX[j] += displacementX;
                this.dispY[j] += displacementY;
            }
        }
    }
};

/**
 * Function: calcRepulsion
 *
 * Calculates the repulsive forces between all laid out nodes
 */
mxFastOrganicLayout.prototype.calcRepulsion = function()
{
    var vertexCount = this.vertexArray.length;

    for (var i = 0; i < vertexCount; i++)
    {
        for (var j = i; j < vertexCount; j++)
        {
            // Exits if the layout is no longer allowed to run
            if (!this.allowedToRun)
            {
                return;
            }

            if (j != i &&
                this.isMoveable[i] &&
                this.isMoveable[j])
            {
                var xDelta = this.cellLocation[i][0] - this.cellLocation[j][0];
                var yDelta = this.cellLocation[i][1] - this.cellLocation[j][1];

                if (xDelta == 0)
                {
                    xDelta = 0.01 + Math.random();
                }

                if (yDelta == 0)
                {
                    yDelta = 0.01 + Math.random();
                }

                // Distance between nodes
                var deltaLength = Math.sqrt((xDelta * xDelta)
                    + (yDelta * yDelta));
                var deltaLengthWithRadius = deltaLength - this.radius[i]
                    - this.radius[j];

                if (deltaLengthWithRadius > this.maxDistanceLimit)
                {
                    // Ignore vertices too far apart
                    continue;
                }

                if (deltaLengthWithRadius < this.minDistanceLimit)
                {
                    deltaLengthWithRadius = this.minDistanceLimit;
                }

                var force = this.forceConstantSquared / deltaLengthWithRadius;

                var displacementX = (xDelta / deltaLength) * force;
                var displacementY = (yDelta / deltaLength) * force;

                this.dispX[i] += displacementX;
                this.dispY[i] += displacementY;

                this.dispX[j] -= displacementX;
                this.dispY[j] -= displacementY;
            }
        }
    }
};

/**
 * Function: reduceTemperature
 *
 * Reduces the temperature of the layout from an initial setting in a linear
 * fashion to zero.
 */
mxFastOrganicLayout.prototype.reduceTemperature = function()
{
    this.temperature = this.initialTemp * (1.0 - this.iteration / this.maxIterations);
};
